The present invention is related to a friction press having a structure characterized by a screw bar with a ram on its lower end and two driving wheels on its upper end which are vertically spaced from each other. The press further has two driving disks which turn in opposite directions on both sides of the driving wheels, and by alternately allowing the upper parts of the inner friction surfaces of the disks and the lower parts of the inner friction surfaces of the same disks to hold the friction circumference of the upper driving wheel and the lower driving wheel, the screw bar will alternately turn in one direction and then another. Consequently, the screw bar and ram will go up and down.
Conventional friction presses usually have a structure wherein one driving wheel is fixed on a screw bar which has a ram on its lower end between two driving disks provided on an identical supporting shaft on both sides of the driving wheel and which turn in the same direction. The turning of the supporting shaft of the driving disks alternates, first in one direction and then another, thus allowing the driving wheel and ram to turn and go up and down. This structure has disadvantages in that the energy of the driving disks is not conveyed to the driving wheel sufficiently because the point of contact and friction between the circumference of the driving wheel and the inner surface of the driving disk is always the same. Furthermore, at the place where the screw bar which turns and goes up and down is supported a distortion occurs at a point of contact between the circumference of the screw bar and the part to support it, thus the turning and going up and down motion of the screw bar is slowed down and the efficiency of press work decreases.